Shibboleths
Gun culture has a few shibboleths. If you use certain terms, people will write you off as either a newbie or an ignoramus.
Bullet
A bullet is an inert piece of metal. A round (also called a cartridge) is comprised of a bullet, a casing, a primer, and gunpowder.
When someone says “bullet”, it’s usually obvious from context whether they mean a round or just a bullet.
Clip
A magazine is part of the gun that holds ammunition. Often the magazine is detachable. This makes reloading quicker and more convenient, as you can eject the empty magazine and insert a full one.
A clip is a device that holds ammunition so that it can be quickly loaded into a magazine. These may be in the form of stripper clips, or the more ornate en-bloc clips used by the M1 Garand.
People usually know from context whether “clip” means “magazine”, but again, using “clip” incorrectly will cause people to judge you.